The 2010 blizzards in the northeastern US they called the ‘Snowpocalypse’ buried this Maryland street, drove senators to deride the idea of global warming, and Columbia University researchers to look at how temperature influences our outlook on climate change. Image credit: BKL, used via Flickr Creative Commons license.

That baking hearing likely played on how we think in a way psychologists had just started to untangle in the previous decade. That is, how we judge things is often dominated by a simple sense of our personal experience, rather than a deeper analysis of evidence available to us. “Numerical judgments are hard, so we grasp at whatever more tangible we can find,” Elke Weber, from Columbia University in New York, explained.

Identifying this tendency to answer an easier question, known as substitution, helped psychologist Daniel Kahneman win a Nobel Prize for Economics. And when it comes to our opinion on climate change, recent temperatures are especially important, Elke and her colleagues have shown over the last three years.

In 2010, a rather different extreme in the US capital drew Elke’s husband Eric Johnson to study this effect. Then, two massive snowstorms struck in one week in February, an event that was dubbed the ‘Snowpocalypse’, leading senators to deride the possibility of climate change. His team therefore looked at whether local weather information gets falsely substituted for global climate in three studies in the US and Australia.

A Roman altar with the Sun in its chariot on the left, and Vulcan, the god of fire and volcanoes on the right. The climate gods long favoured the Roman Empire, with Earth’s orbital dance credited for increasing the amount of solar energy falling on Earth at the time. Image copyright: Nick Thompson, used via Flickr Creative Commons License.

Our climate has changed before. It’s something most of us realise and can agree on and, according to Skeptical Science, it’s currently the most used argument against human-caused warming. If such changes have happened naturally before, the argument goes, then surely today’s warming must also be natural. It’s an appealing idea, with an instinctively ‘right’ feel. Nature is so huge compared to us puny humans, how can we alter its course? The warming we’re measuring today must just be a natural fluctuation.

It’s such an appealing argument that at the beginning of the 20th century that’s just what many scientists thought – that humans couldn’t alter Earth’s climate. In the time since, our knowledge has come a long way. We’ve explored space, become able to build the electronics that are letting you read this, and climate science has likewise advanced and benefited from these advances.

So what do we know today that might convince the sceptical scientists of 115 years ago that we’re warming the planet? Recently, Richard Mallett, one of my Twitter friends who describes himself as sceptical about mainstream climate science, made a point that serves as an excellent test of our current knowledge:

@andyextance Climate science should be able to explain the Holocene, Roman, Medieval and current warmings and the cold periods in between.

Of the historical warmings he’s referring to, perhaps the least familiar is the Holocene, which is ironic, as the Holocene is now. It’s the current period of geological time that started at the end of the last ice age, 11,700 years ago. By 1900 scientists would have known the term, but they couldn’t explain why it wasn’t as icey as before.

Three variables of the Earth’s orbit—eccentricity, obliquity, and precession—affect global climate. Changes in eccentricity (the amount the orbit diverges from a perfect circle) vary the distance of Earth from the Sun. Changes in obliquity (tilt of Earth’s axis) vary the strength of the seasons. Precession (wobble in Earth’s axis) varies the timing of the seasons. For more complete descriptions, read Milutin Milankovitch: Orbital Variations. Image credit: NASA/Robert Simmon.

The explanation we have today comes thanks to the calculations Milutin Milanković worked out by hand between 1909 and 1941. Milutin showed that thanks to the gravitational pull of the Moon, Jupiter and Saturn, Earth’s orbit around the Sun varies in three ways. Over a cycle of roughly 96,000 years our path varies between more circular and more oval shapes. The other two ways come because Earth’s poles are slightly tilted relative to the Sun’s axis, which is why we have seasons. The angle of that tilt shifts over a roughly 41,000 year cycle. Earth also revolves around that tilted axis, like a spinning top does when it slows down, every 23,000 years.

At the Transformational Climate Science conference in my home town, Exeter, UK, earlier this month, senior IPCC author Ottmar Edenhofer discussed the ‘battle’ with governments on his part of the report. Another scientist who worked on the report highlighted confidentially to me how unusual the omission was.

To me, it’s more surprising that this hasn’t happened more often, especially when you look more closely at the latest report’s findings. There’s concrete certainty that warming is happening, and it’s extremely likely that humans are the dominant cause, it says. Governments have even – in some cases, begrudgingly – already signed up to temperature and CO2 emission targets reflecting this fact.

The inadequacy of those words is becoming ever more starkly obvious. Ottmar stressed that the emissions levels agreed at the United Nations’ Climate Change Conference in Cancún, Mexico, in November 2010, would likely need later emissions cuts the likes of which we’ve never seen before to avoid dangerous climate change. The latest IPCC report shines a floodlight on that inertia, which understandably cranks up the tension between researchers and politicians.

Ottmar was one of two co-chairs who led the ‘working group three’ (WGIII) section of the IPCC report that looks at how to cut greenhouse gas emissions. He stressed that the need to make these cuts comes from a fundamental difference between the risks that come from climate change and the risks of mitigation. We can heal economic damage arising from cutting emissions – reversing sea level rise isn’t so easy.

This is part three of this profile. Read part one here and part two here.

In response to the revelations of his ongoing research, NASA scientist Jim Hansen has become increasingly active in campaigning to halt climate change over the past decade. Image credit: Greenpeace

By December 6, 2005, NASA Goddard Institute of Space Studies’ (GISS) temperature record was already sending a clear message: worldwide, 2005 would likely be the warmest year so far. For GISS director Jim Hansen, speaking to the annual American Geophysical Union conference, arguably the world’s largest environmental research meeting, it seemed fair to reveal. For several listening journalists it was newsworthy enough for them to cover Jim’s talk. But it would anger some of Jim’s colleagues at NASA headquarters enough to try to stop him talking to the media. In the process they’d drag him outside the world of pure research he was most comfortable in. “The undue influence of special interests and government greenwash pose formidable barriers to a well-informed public,” Jim would later write about the situation. “Without a well-informed public, humanity itself and all species on the planet are threatened.”

The comments came during a lecture in honour of Dave Keeling, the CO2 tracking pioneer, who’d died of a heart attack in June that year. Soothing Jim’s hesitation, Dave’s son Ralph stressed he was continuing the work of his father, who had even been discussing one of Jim’s papers minutes before his death. And so Jim had brought together evidence showing that Earth’s climate was nearing a ‘tipping point’ beyond which it will be impossible to avoid dangerous changes. However, warming from 2000 onwards might still be kept below the 1°C level that Jim at that time considered hazardous if CO2 levels in the air were held at about 450 parts per million (ppm). Emissions of other greenhouse gases would also need to be significantly reduced. The message was clear: how we get our energy would must change, mainly by shifting away from coal and the vast volumes of CO2 burning it produces.

NASA headquarters was already reviewing all publicity on climate change research, but the latest coverage would force it into even more severe action. The following week it laid out new restrictions on Jim’s ability to comment publicly, and the global GISS temperature record was temporarily taken off the internet. Prominent amongst those setting the new conditions was NASA’s new head of public affairs, appointed by George Bush’s administration, David Mould. His previous jobs included a senior media relations role at the Southern Company of Atlanta, the second largest holding company of coal-burning power stations in the US. Only one company had donated more to the Republican Party than the Southern Company during George Bush’s 2000 election campaign: Enron. Read the rest of this entry »

Jim Hansen giving testimony at a US Congressional hearing in 1988, where he’d declare 99% certainty that humans are changing the climate. Image credit: NASA

“It’s time to stop waffling so much and say that the evidence is pretty strong that the greenhouse effect is here.” It’s a comment that wouldn’t sound out of place today, but Jim Hansen made it 26 years ago, on June 23, 1988, amid record 38°C temperatures in Washington DC. Jim said it to reporters after telling a Congressional hearing he was 99% certain the world is getting warmer thanks to human-made greenhouse gases.

Jim’s 1980s media bombshells led journalist Robert Pool to liken him to a religious ‘witness’, ‘someone who believes he has information so important that he cannot keep silent’. However, he still felt shy and awkward, preferring to immerse himself in pure science, and so would turn down almost all invitations to speak out for another decade. Jim’s efforts during that period would then help build even stronger evidence on global warming. But with extra motivation provided by clashes with the US government and the arrival of his grandchildren he would return to bear witness more forcefully than ever.

Before his self-imposed media ban Jim would make headlines one more time in 1989, after giving written evidence to a hearing convened by then US senator Al Gore. The testimony reaching the hearing had been altered by the White House to make his conclusions about the dangers of global warming seem less certain. When Jim sent the future vice-president a note telling him this, he alerted the media, turning their scheming into the lead story across all TV networks that evening. John Sununu, aide to then president George H. W. Bush, would then try to get Jim fired for his troubles. But Republican senator John Heinz intervened on Jim’s behalf, and he kept his job.

Normally during a total lunar eclipse, like this one on April 15, 2014, you can still see the moon, but in 1963 Jim Hansen saw it disappear completely. Explaining why would send him on a scientific journey to Venus, before coming back down to Earth. Image credit: NASA

Jim Hansen’s life changed on the evening the moon disappeared completely. In a building in a cornfield Jim and fellow University of Iowa students Andy Lacis and John Zink, and their professor Satoshi Matsushima, peered in surprise through a small telescope into the wintry sky. It was December 1963, and they had seen the moon replaced by a black, starless circle during a lunar eclipse. The moon always passes into Earth’s shadow during such eclipses, but usually you can still see it.

At first they were confused, but then they remembered that in March there had been a big volcanic eruption. Mount Agung in Indonesia had thrown tonnes of dust and chemicals into the air: perhaps that was blocking out the little light they’d normally have seen? With a spectrometer attached to their telescope they measured the moon’s brightness, data Jim would then base his first scientific research on. Using this record to work out the amount of ‘sulphate aerosol’ particles needed to make the moon disappear, Jim began a lifelong interest in planets’ atmospheres. That would lead him to become director of the NASA Goddard Institute of Space Studies (GISS), where he has led the way in exposing the threat from human CO2 emissions.

Jim was born in Iowa in 1941, the fifth of seven children of a farmer, who had left school at 14, and his wife. As he grew up they moved into the town of Denison, his father becoming a bartender and his mother a waitress, and Jim spending his time playing pool and basketball. Jim claims he wasn’t academic, but found maths and science the easiest subjects, always getting the best grades in them in his school. Though his parents divorced when he was young, public college wasn’t expensive at the time, meaning Jim could save enough money to go to the University of Iowa.

The university had an especially strong astronomy department, headed by James Van Allen, after whom brackets of space surrounding the Earth are named. These ‘Van Allen Belts’ are layers of particles that he discovered, held in place by the planet’s magnetic field. Satoshi Matsushima, a member of Van Allen’s department, could see Jim and Andy’s potential and convinced them to take exams to qualify for PhD degrees a year early. Both passed, with Jim getting one of the highest scores, and were offered NASA funding that covered all their costs.

A few months later, it was Satoshi who suggested measuring the eclipse’s brightness, feeding Jim’s interest in atmospheres on other planets. “Observing the lunar eclipse in 1963 forced me to think about aerosols in our atmosphere,” Jim told me. “That led to thinking about Venus aerosols.” In an undergraduate seminar course Jim had given a talk about the atmospheres of outer planets, which James Van Allen had attended. The elder scientist told him that recently measured data was suggesting Venus’ surface was very hot. Aerosols stopped light reaching the Earth during the eclipse – could they be warming up Venus by stopping heat escaping, Jim wondered? That would become the subject of his PhD, and Satoshi and James Van Allen would be his advisors. Read the rest of this entry »

Wheat ear infected with Fusarium ear blight (FEB), giving the ear a pinkish color. The disease could be set to increase in countries like China and the UK with climate change, Bruce Fitt and his teammates have found, suggesting resistant varieties should be developed. Photo credit: CIMMYT.

As the planet warms, China’s wheat crops will be threatened by more frequent epidemics of ‘fusarium ear blight’ (FEB), scientists in the UK and China have projected. Bruce Fitt from the University of Hertfordshire in Hatfield, UK, and his teammates forecast levels of the disease in the Anhui and Hubei provinces from 2021-2050. Whereas in the worst affected regions in 2001-2010 around one-sixth of all ears were infected, this was the lowest disease level the researchers found in their future scenario. In the worst-hit areas, FEB infected more than a third of all ears. “This has implications for crop breeding because it takes 10-15 years to breed a new cultivar,” Bruce told me. “If you know the disease is going to become more important then you need to get on and start breeding now rather than waiting until the disease hits you.”

Today, over a billion people don’t have enough to eat, and further population growth and climate change are set to put the world’s food supplies under even greater strain. To help ease that pressure, Bruce and other scientists are working to understand and help improve control of crop diseases like FEB. While some crop diseases will worsen in the future, not all will, he stressed. “For example, you might have a disease that is spread by rainsplash in summer and then it’s predicted that there will be far less rainfall in summer,” he explained. “Then you would expect that with climate change the importance of that disease would diminish.” If governments, farmers and seed suppliers know which diseases are likely to get worse, they can prioritise developing strategies to contol them, like breeding disease resistant varieties.

To make useful forecasts for which diseases will worsen, scientists build models that include weather data, how crops grow and how the disease pathogen spreads through the crop. “In this particular instance the wheat is susceptible only at flowering,” Bruce said. “It may be in flower for a few days. If it doesn’t get the pathogen inoculum and the right weather conditions at that time it will not get the disease.” Climate change can both alter flowering times and the chances of warm, wet weather that make infection more likely. When wheat gets infected, even if it can be harvested it is more likely to contain poisonous mycotoxins. “If it’s full of mycotoxins then it can’t be eaten by man or beast, so it’s just wasted,” Bruce added. Read the rest of this entry »